This cunning predatory sea snail is a Yellow Wentletrap Sea Snail (Epitonium billeeanum). It feeds exclusively on Tubastrea coral, and is the only known predator of Orange Cup Coral (Tubastraea coccinea).
This particular speciman was found on the coral reef wall that surrounds Racha Yai Island off the coast of Phuket, Thailand in the Andaman Sea.